New two dimensional NMR methods will be developed to study the interactions of substrates with biomolecules. These techniques will utilize the nuclear Overhauser effect between heternuclear species. It will be possible to selectively observe spectra of protons in the vicinity of a substrate binding site without interference from resonance of protons in the rest of the molecule. One of the methods to be developed utilizes heteronuclear spin locking, and will enable us to use nuclei such as TI-205 and Pt-195 as probes. This is not possible with existing methods because the relaxation of these species are dominated by mechanisms other than dipole-dipole interactions with protons. We will use these new techniques, together with established NMR methods and molecular modeling, to study the interactions of the metal ions, lithium and thallium with lasalocid-A,a polyether antibiotic. We will also use these methods to study the interactions of the antibiotic Vancomycin with small peptides. These later studies will confirm known interactions between these species and should yield additional details regarding substrate binding, providing a better understanding of the molecular level phenoma responsible for Vancomycin's antibacterial activity.